The purpose of this project is to characterize the lipase that initiates the hydrolysis of dietary fat. This "pharyngeal lipase" produces amphiphilic lipids in the stomach as the first step in the digestion of fat. The enzyme has been partially purified from serous glands of the tongue in rat and from the secretions of a man with esophageal fistula. In both the enzyme activity is present in 2 elution peaks by gel chromatography with estimated molecular sizes of 2 x 10 to the 5th power and 2 x 10 to the 6th power. These may represent polymeric or adsorbed forms of the enzyme. In purified form the enzyme is labile whereas in crude form (juice or frozen glands) it is very stabile. Further efforts will be directed towards characterizing the enzyme and investigating the physiological regulation of its secretion. This enzyme could play an important role in fat digestion in infants.